Heat Exchanger

ABSTRACT

Disclosed herein is a heat exchange apparatus. The apparatus comprises one or more double walled conduit, each having an outer conduit and an inner conduit located coaxially inside the outer conduit. The conduits define a first fluid passageway for cold water at a first temperature. A drain defines a second fluid passageway for grey water at a second temperature and is located in the drain and downstream of the grey water flowing therethrough. The grey water when flowing in the second fluid passageway effects heat transfer to the cold water flowing in the first fluid passageway across the inner and outer conduits.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 61/229,424, filed on Jul. 29, 2009 and U.S. Provisional Patent Application Ser. No. 61/323,441, filed on Apr. 13, 2010; the contents of each of these applications are hereby incorporated by reference.

TECHNICAL FIELD

The present concerns heat exchangers, and more particularly to single and double-walled heat exchanges.

BACKGROUND

Heat exchangers are well-known and widely used in a number of environments to recover thermal energy from fluids. The thermal energy, if not recovered, would be lost to the environment. Heat exchangers work by transferring heat from one fluid to another via a solid wall, which separates the two fluids. This straightforward principle has been used to recover heat from waste water (so called “grey water”) in, for example, household shower and bath systems. A number of designs of heat exchangers are described as follows.

Published U.S. Patent Application No. 2008/0047698 A1 discloses a helical copper fin that is tightly wrapped onto a single or double wall copper drain pipe and an outer shell that is made of CPCV or any other suitable material. It is disclosed that copper is a preferred material because it eliminates differential expansion effects, while increasing the effective contact area but acting like a heat fin. One or more parallel helical flow paths, with or without a variable helix pitch induces turbulence and mixing, which can also be used to adjust pressure drop. The helical fin has an outer diameter that is slightly less in the diameter of the drain pipe into which it can be inserted. This insertion forcibly ensures metal to metal contact between the fin and the tube. Fluids that enter the inner helical path cause heat exchange with a fluid flowing within the outer helix 16 in a counter or coil flow direction. However, this application does not appear to disclose a double-walled helical conduit in which cold water flows. Furthermore, the fins are solid and appear to operate by contacting a drain pipe and therefore provide heat exchange via the fins.

U.S. Pat. No. 4,314,397 discloses a solar liquid-to-liquid heat exchanger. The heat exchanger has a first tubular coil, which is made of a first heat-conductive tube material. The heat exchanger also has a second tubular coil that is made of a heat conductive tube material and is disposed in a tubular arrangement that is co-axial with the first coil. A cross-sectional view of the coils shows that a fixing means holds the coils together. The coils are to be single-walled. The fixing means, which may be solder, may have a conductive heat transfer coefficient, which is better than the heat transfer coefficient of the material from which each coil is made. A number of variations of coil design include an oval configuration, a rectangular configuration, and a frustoconical configuration. Solder is used to mechanically connect the coils together.

U.S. Pat. No. 4,443,389 discloses a heat exchanger apparatus in which a cooling tower includes coils that carry heated water from a facility. The coils include a plurality of tubular designs. A helical fin is coiled around a central portion within the coil, which presumably acts as a turbulator. Various other turbulator structures are illustrated throughout. A tube includes an inner core appears itself to be a tube; but does not appear to be immersed in waste grey water. In this patent, cooling fluid flows through the coils and water is distributed over the coils so as to enhance heat transfer between the cooling medium on the exterior surfaces of the coil and heat exchange material flowing through the coil. The heat exchanger in this case appears to be directed towards providing cool air to the exterior of the cooling tower. Thus, air drawn through the louvers is cooled and is expelled from the apparatus. Both U.S. Pat. Nos. 4,314,397 and 4,443,389 are directed towards heat exchange applications that are not associated with recapturing heat from waste grey water.

Thus, there is a need for an improved heat exchange apparatus, in which the fluids do not contact each other and which provides efficient thermal energy transfer across double heat exchanger walls over a helical or serpentine pathway.

BRIEF SUMMARY

We have designed a novel passive fluid-to-fluid heat exchange apparatus, which uses a unique helical or serpentine double walled conduit to provide unexpectedly high effectiveness in heat recapture from waste water (also known as “grey water”) commonly found in household shower and bath systems. Furthermore, we have discovered that single or double walled conduits can be used against a single drain plate to create a gravity film of grey water, which caused a surprising increase in heat exchange properties. The double wall conduits advantageously provide heat transfer that is the same as single walled conduits even though the leak path, which is located between the two walls is functional (i.e. water can pass through the walls at low pressure i.e. less than 5 psi).

Accordingly, in one aspect there is provided a heat exchange apparatus, the apparatus comprising:

a) at least one double walled conduit having an outer conduit and an inner conduit located coaxially inside the outer conduit, and defining a first fluid passageway for a first fluid at a first temperature; and

b) a drain defining a second fluid passageway for a second fluid at a second temperature, the double walled conduit being located in the drain and downstream of the second fluid flowing therethrough, such that the second fluid when flowing in the second fluid passageway effects heat transfer to the first fluid flowing in the first fluid passageway across the inner and outer conduits.

The inner conduit includes an outer wall, the outer conduit includes an inner wall, the outer wall being located against the inner wall to define a leak passageway therebetween. The outer conduit includes an inner knurled surface that is pressed against the outer wall of the inner conduit to define the leak passageway. The double walled conduit is helical. The apparatus includes an outer helical double wall conduit, a central helical double wall conduit and an inner helical double wall conduit. The outer, central and inner helical double walled conduits are assembled concentrically. The circumference of the helices of the double wall conduits decreases from the outer conduit to the inner conduit. The helical conduits are coiled in the same direction. The helical conduits are coiled in a counterclockwise direction. The helical conduits are coiled in a clockwise direction. Each conduit includes a bend located at an upper end of the assembled helical conduits. The first and second fluids flow in a contra-flow manner through the heat exchange apparatus. The drain is a drain conduit. The drain conduit includes an upper drain portion connected to a drain trap. A bypass conduit is connected to the drain conduit, the bypass conduit having a mesh for blocking particulate material. The apparatus includes a deflector located in a central core of the drain conduit. The apparatus includes a vertically orientated conduit located at the top of the central core of the drain conduit and having a plurality of holes located therein. A cap is located on top of the vertically orientated conduit for temporarily blocking a central bypass channel. The cap is operated manually or automatically. The deflector is a cone with side plates for forcing the second fluid away from the conduit. A plurality of helical conduits are stacked adjacent each other in the drain conduit. The apparatus includes four stacked helical conduits. The helical conduits include a common first fluid inlet and a common first fluid outlet. The apparatus is orientated orthogonal to the ground. The apparatus is orientated horizontal to the ground. The apparatus is connected to a drain trap in a shower. The double walled conduit is serpentine. At least a portion of the serpentine double walled conduit is located in the drain. At least one serpentine double wall conduit is connected to an elongate housing having two sidewalls and passes through an upper set of openings located in the sidewalls. A first plurality of conduit elbows extend away from the sidewalls along substantially the entire length of the elongate housing. A second serpentine double wall conduit is connected to the elongate housing and passes through a lower set of openings located in the sidewalls. A second plurality of conduit elbows extend away from the sidewalls along substantially the entire length of the elongate housing. A plurality of fins are mounted around the outer wall of the serpentine conduits, the fins being disposed parallel to each other and extend substantially the entire length of the elongate housing. The apparatus includes a turbulator located in the drain or the helical conduit. The drain is a drain plate having a drain plate inlet and a drain plate outlet and a drain plate surface through which at least a portion of the double wall conduit extends, the drain plate surface being of sufficient area to define the second fluid passageway for the second fluid such that the second fluid flows as a fluid film along the second fluid passageway. A plurality of double walled conduits extend parallel along the drain plate. The drain plate is orientated horizontal relative to the ground. The drain is angled relative to the ground. A plurality of serpentine double walled conduits. The serpentine conduits are sufficiently spaced apart top allow the second fluid to flow thereover. The drain is a trench drain. The first fluid is cold water. The second fluid is grey water. A heating wire is located inside the double walled conduit. A heating wire is located around the double walled conduit.

In another aspect, there is provided a heat exchange apparatus comprising:

a) at least one single walled conduit defining a first fluid passageway for a first fluid at a first temperature; and; and

b) a drain plate having a drain plate inlet and a drain plate outlet and a drain plate surface against which at least a portion of the single wall conduit is located in intimate contact, the drain plate surface being of sufficient area to define a second fluid passageway for a second fluid such that the second fluid flows as a fluid film along the second fluid passageway so as to effect heat transfer to the first fluid flowing in the first fluid passageway across the single walled conduit.

In another aspect, there is provided a heat exchange apparatus comprising:

a) at least one single walled conduit defining a first fluid passageway for a first fluid at a first temperature; and; and

b) a drain plate having a drain plate inlet and a drain plate outlet and a drain plate surface against which at least a portion of the single wall conduit is located in intimate contact, the drain plate being located generally orthogonal to the ground, the drain plate surface being of sufficient area to define a second fluid passageway for a second fluid such that the second fluid flows as a fluid film along the second fluid passageway so as to effect heat transfer to the first fluid flowing in the first fluid passageway across the single walled conduit.

In another aspect, there is provided a heat exchange apparatus comprising:

a) at least one single walled conduit defining a first fluid passageway for a first fluid at a first temperature; and

b) a drain plate having a drain plate inlet and a drain plate outlet and a drain plate surface against which at least a portion of the single wall conduit is located in intimate contact, the drain plate being located generally orthogonal to the ground, the drain plate surface being of sufficient area to define a second fluid passageway for a second fluid, the drain plate being angled relative to the ground, such that the second fluid flows as a fluid film along the angled second fluid passageway so as to effect heat transfer to the first fluid flowing in the first fluid passageway across the single walled conduit.

In another aspect, there is provided a heat exchange apparatus comprising:

a) at least one single walled conduit defining a first fluid passageway for a first fluid at a first temperature; and; and

b) a drain plate having a drain plate inlet and a drain plate outlet and a drain plate surface against which at least a portion of the single wall conduit is located in intimate contact, the drain plate being located generally horizontal relative to the ground, the drain plate surface being of sufficient area to define a second fluid passageway for a second fluid such that the second fluid flows as a fluid film along the second fluid passageway so as to effect heat transfer to the first fluid flowing in the first fluid passageway across the single walled conduit.

The first and second fluids flow in a contra-flow manner through the heat exchange apparatus. The apparatus is connected to a drain trap in a shower. The single walled conduit is serpentine. At least one serpentine double wall conduit is connected to an elongate housing having two sidewalls and passes through an upper set of openings located in the sidewalls. A first plurality of conduit elbows extend away from the sidewalls along substantially the entire length of the elongate housing. A second serpentine single walled conduit is connected to the elongate housing and passes through a lower set of openings located in the sidewalls. A second plurality of conduit elbows extend away from the sidewalls along substantially the entire length of the elongate housing. A plurality of fins are mounted around the outer wall of the serpentine conduits, the fins being disposed parallel to each other and extend substantially the entire length of the elongate housing. The apparatus includes a turbulator located in the conduit. A plurality of single walled conduits extends parallel along the drain plate. The serpentine conduits are sufficiently spaced apart to allow the second fluid to flow thereover. The drain is a trench drain. The first fluid is cold water. The second fluid is grey water. A heating wire is located inside the single walled conduit. A heating wire is located around the single walled conduit.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of that described herein will become more apparent from the following description in which reference is made to the appended drawings wherein:

FIG. 1 is a schematic view of a household shower/bath system showing the location of a heat exchanger;

FIG. 2 is a perspective view of a vertical helical heat exchange apparatus located below a drain trap

FIG. 3 is a perspective view of the heat exchanger of FIG. 2 showing three helical cold water conduits;

FIG. 3A is a perspective cross sectional view taken along line 3-3′ in FIG. 3;

FIG. 4 is a side view of FIG. 3A showing the double wall feature of the helical conduits;

FIG. 4A is a cross sectional view of a double walled conduit;

FIG. 5 is a perspective view of the helical heat exchange apparatus of FIG. 2 showing the relative location of the three helical conduits;

FIG. 6 is an exploded perspective view of the heat exchange apparatus of FIG. 2 showing the three helical conduits;

FIG. 6A is a perspective view of a heat exchange apparatus showing conduit bends;

FIG. 6B is a perspective view of an alternative vertical heat exchange apparatus;

FIG. 6C is a perspective exploded view of the apparatus of FIG. 6B;

FIG. 6D is a perspective view of a plurality of stacked helical double walled conduits;

FIG. 7A is a schematic representation of an anti blocking feature showing a bypass conduit;

FIG. 7B is a schematic representation of another anti-blocking feature showing an elongate pipe with a plurality of holes;

FIG. 7C is a schematic representation of another anti-blocking feature showing a cap and mesh;

FIG. 7D is a schematic representation of another anti-blocking feature showing a deflector;

FIG. 7E is a top view of the deflector of FIG. 7D;

FIG. 8 is a perspective view of a horizontal heat exchanger;

FIG. 8A is a cross sectional view taken along line 8-8′ showing the location of fins and two serpentine conduits;

FIG. 9 is a perspective detailed view of a portion of the heat exchanger of FIG. 8 showing details of the serpentine conduits and fins;

FIG. 9A is a perspective partial cutaway view of FIG. 9 showing the location of holes and the respective serpentine conduits;

FIGS. 10A-C are diagrammatic representation of a number of surface turbulation patterns;

FIGS. 11A-G are diagrammatic representations of a number of turbulator inserts;

FIGS. 12A-E are diagrammatic representations of a number of grey water inserts;

FIG. 13 is a perspective view of a film heat exchanger apparatus;

FIG. 14 are perspective partial cutaway views of the film heat exchange apparatus of FIG. 13 showing the location of the cold water conduits;

FIG. 15 is a detailed view of an end portion of the film heat exchange apparatus of FIG. 13 showing the location of the cold water conduits and the drain plate;

FIG. 15A is a perspective view of a shell of a horizontal heat exchange apparatus;

FIG. 15B is a perspective view of serpentine conduits located inside the apparatus of FIG. 15A;

FIG. 16 is a top view of an alternative film heat exchange apparatus showing the location of the cold water conduits;

FIG. 16A is a cross sectional view of the cold water conduits of FIG. 16;

FIG. 17A is an exploded view of a manifold showing the location of the double wall conduit in the manifold;

FIG. 17B is a detailed view of the manifold of FIG. 17A showing the conduit located in the manifold;

FIG. 18 is a schematic representation of a gravity thermosyphon for use with any heat exchange apparatus described herein;

FIG. 19 is a front view of an alternative heat exchange apparatus disposed in a vertical orientation;

FIG. 20 is a schematic representation of the heat exchange apparatus of FIG. 19 showing the location of the cold water conduits adjacent a drain plate; and

FIG. 21 is a perspective view of a heat exchange apparatus located in a trench drain.

DETAILED DESCRIPTION Definitions

Unless otherwise specified, the following definitions apply:

The singular forms “a”, “an” and “the” include corresponding plural references unless the context clearly dictates otherwise.

As used herein, the term “comprising” is intended to mean that the list of elements following the word “comprising” are required or mandatory but that other elements are optional and may or may not be present.

As used herein, the term “consisting of” is intended to mean including and limited to whatever follows the phrase “consisting of”. Thus, the phrase “consisting of” indicates that the listed elements are required or mandatory and that no other elements may be present.

As used herein, the term “turbulator” when referring to either a surface or to an insert having a surface that acts as a turbulator, is intended to mean that the surface has a plurality of projections extending away from the surface. Surface turbulators and inserted turbulators are used to increase convection rates and heat transfer coefficients at heat exchange surfaces in fluid passageways in order to provide high performance in compact heat exchange assemblies, and to orientate fluids into a pre-defined direction often resulting in chaotic paths. Examples of types of turbulators include, but are not limited to, corrugations, peaks and troughs, nubbins, raised chevrons having a gap between, fish scales, raised zigzag moldings, meshes, criss cross oriented wires, porous materials, and the like. Turbulators may comprise uniform or non-uniform surface profiles, textures, open cell structures, and shapes. Fluid passageway geometry allows control of fluid flow via solid or semi-solid mechanical structures and may be constructed from laminate composites, molded parts, and meshes of plastics, ceramics, metals or other materials.

As used herein the term “fluid” is intended to mean gas or liquid. Examples of liquids suitable for use with the heat exchangers described herein include, but are not limited to, water, hydraulic fluid, petroleum, glycol, oil and the like, and steam.

Referring now to FIG. 1, a heat exchange apparatus is shown generally at 10 in use with a household shower and bath system 12. The household shower and bath system 12 includes a water heater 14, a hot water line 16, a cold water line 18, a warm water line 20, a mixing valve 22, a shower head 24 and a drain trap 26. The hot and warm water lines 16, 20 are each connected to the mixing valve 22, the temperature of the water exiting the shower head 24 being controlled by the user operating the mixing valve 22. The cold water line 18 is connected to the heat exchange apparatus 10 and feeds cold water 25 (a first fluid) into the apparatus 10. The warm water line 20 is connected to the heat exchange apparatus 10 and the mixing valve 22. The drain trap 26 receives drain water 28 (so called “grey water”) (a second fluid) from the shower/bath tub and communicates the drain water to the heat exchange apparatus 10. After flowing through the heat exchange apparatus 10, the grey water 28 exits the household shower system 12 to a main drain (not shown). It should be noted that although an example of a household shower/bath system is illustrated, the heat exchange apparatus described may also be used for other applications that require heat exchange between two fluids. Furthermore, it is to be noted that any of the heat exchangers described hereinbelow can also be connected to the system 12, either directly to the drain trap 26 or downstream of the P-trap.

I. Helical Double Walled Heat Exchange Apparatus

Referring now to FIGS. 2, 3, 3A, 4 and 4A, a helical (or coiled) double wall heat exchange apparatus is shown generally at 10. The apparatus 10 is for use in household applications and can be connected to the drain trap 26 in a typical household shower, bath or sink. The apparatus 10 may also be used for industrial or commercial applications in which high volumes of waste grey water are used. Advantageously, the apparatus provides thermal energy recapture of about 80% in a heat exchanger with a vertical height of 20-inches and a nominal inner diameter 3-inches with pressure loss below 5 psi at 10 litres per minute flow. By contrast, a Delstar mesh vertical heat exchanger has an effectiveness in the range of 70% for a heat exchanger of 72-inches with comparable pressure loss. The apparatus 10 is typically used in the vertical orientation, i.e. is orthogonally disposed to the ground. The apparatus 10 comprises at least one helical double wall conduit 30 and a drain conduit 32. The helical double wall conduit 30 is a first fluid passageway 34 for the first fluid 25, typically cold water, at a first temperature, typically about 10° C. The helical double wall conduit 30 includes an outer conduit 36 and an inner conduit 38 located coaxially inside the outer conduit 36, which define the first fluid passageway 34. The drain conduit 32 defines a second fluid passageway 40 for the second fluid 28, typically grey water, at a second temperature, typically about 40° C. The drain conduit 32 includes an upper drain portion, which is connected to the drain trap 26 such that grey water flows from the shower into the drain conduit 32. The helical double walled conduit 30 is located in the drain conduit 32 and downstream of the second fluid 28 flowing therethrough. The second fluid 28 when it flows in the second fluid passageway 40 effects thermal energy (heat) transfer to the first fluid 25 flowing in the first fluid passageway 34 across the inner conduit 38 and the outer conduit 36.

Referring to FIG. 4A, the inner conduit 38 includes an outer wall 42, the outer conduit 36 includes an inner wall 44, the outer wall 42 being located against the inner wall 44 to define a leak passageway 46 therebetween, which can vent to the atmosphere if either of the inner or outer walls 42, 44 ruptures or is pierced. In one example, the outer conduit 36 includes an inner knurled surface that is pressed against the outer wall 42 of the inner conduit 38 to define the leak passageway 46. In another example, the inner wall 44 of the outer conduit 36 is smooth and is pressed against the outer wall 36 of the inner conduit 38 with sufficient force to leave a leak passageway 46 therebetween.

Cross-connection of plumbing devices is ruled by strict, but variable, local regulations, where grey water and fresh cold water are present within the same heat exchange apparatus. Thus, a double wall design is desirable over any other protection means to prevent fresh water contamination by grey water in the event of system failure, such as if the heat exchanger wall is ruptured or pierced.

As best illustrated in FIGS. 3, 5 and 6, the heat exchange apparatus 10 includes three helical double wall conduits 30A, 30B and 30C, the outer helical double wall conduit 30A, the central helical double wall conduit 30B and the inner helical double wall conduit 30C, which are assembled concentrically within an outer wall 29 and an inner wall 27 of the drain conduit. The circumference of the helices of the double wall conduits 30A, 30B and 30C decreases from the outer conduit 30A to the inner conduit 30C. The helical conduits 30A, 30B and 30C are located in the drain conduit 32 and assembled concentrically, yet are sufficiently spaced apart to define the second fluid passageway through which the grey water can flow. Each of the helical conduits 30A, 30B and 30C are coaxially orientated and are coiled in the same direction. In the examples illustrated, the helical turns in conduits 30A, 30B and 30C are coiled in a counterclockwise direction. However, one skilled in the art will recognize that the helical coils can also turn in a clockwise direction. Thus, waste grey water flowing along the second fluid passageway contacts the outer surfaces of the helical coils 30A, 30B and 30C, which act as thermal energy exchange surfaces, as it moves along the second fluid passageway and is able to efficiently transfer its thermal energy across the double wall of the helical conduits to the first fluid flowing in the first fluid passageway. It is also possible that instead of the helices 30A. 30B, and 30C being concentrically assembled, they may also be located offset from each other. Optionally, a low voltage heating wire, heating coil or heating tape (not shown) may be located inside the conduits 30A, 30B, and 30C. This provides not only turbulation of the cold water, but also provides additional heat so that the heat exchanger 10 can provide all the heat required for the application (i.e. no longer passive and does not need to be combined with an external heating system).

Referring now to FIG. 6A, the heat exchange apparatus 10 may have additional features such as a plurality of bends 31 located at the upper end of the assembled conduits. Each bend 31 is connected to a double walled conduit. The bends 31 are made in each conduit before assembly and then the conduit is coiled to create two helices, one on top of the other. It is not the same as a double helix, which has two helices made from one conduit, but the helices are on two separate diameters. Advantageously, the location of the bends 31 allows the cold water connectors 33,35 to be located either at the top of the apparatus 10 or the bottom, which is useful in applications where the apparatus 10 is to be located in a space-restricted area. In one example, the first and second fluids flow in a contra-flow manner through the heat exchange apparatus 10. It is also possible to have the fluids flow in a parallel flow manner. A first temperature T1 of the first fluid 25 entering the first fluid passageway 34 is typically less than the second temperature T2 of the first fluid 25 as it exits the first fluid passageway 34. Similarly, the third temperature T3 of the second fluid 28 entering the second fluid passageway 40 is greater than the fourth temperature T4 of the second fluid 28 as it exits the second fluid passageway 40. By way of example, T1 is typically 10° C. for cold water, T3 is typically 40° C. for grey water and T4 is typically 30° C. for grey water exiting the heat exchanger 10, and T2 is typically 24° C. for warmed water entering the warm water line 22 from the heat exchanger 10. To measure the effectiveness of the heat exchange apparatus, the following equation is used:

${Effectiveness} = \frac{T_{{cold}\mspace{14mu} {out}} - T_{{cold}\mspace{14mu} {in}}}{T_{{grey}\mspace{14mu} {in}} - T_{{cold}\mspace{14mu} {in}}}$

where T denotes temperature in ° C.

At least one of the fluids flows through its respective passageway under pressure, the other fluid flowing through its respective passageway at atmospheric pressure. Typically, the second fluid (the cold water) flows under pressure at approximately 50 psi along the first fluid passageway 34.

Referring to FIGS. 6B, 6C and 6D, an alternative embodiment of a vertical heat exchange apparatus is shown generally at 60. The apparatus 60 comprises an outer shell 62, a grey water inlet 64, a grey water outlet 66, a cold water inlet 68 and a cold water outlet 70. An inner shell 72 houses a plurality of helical double wall conduits 74, which are stacked adjacent each other (in the example illustrated four conduits are provided). The conduits 74 each receive cold water from the common cold water inlet 68 and the warmed water exits the heat exchanger via the common outlet 70. The multiple stacked helices provide for heat exchange with reduced pressure loss compared to a single helix of the same height.

Referring to FIGS. 7A through 7E, illustrate a number of features, which may be added to the vertical helical double wall heat exchange apparatus to prevent blocking of the heat exchanger. Although the features are used primarily for sinks, they may also be used in other applications. FIG. 7A illustrates a bypass conduit 40 connected to the drain conduit, which includes a mesh 42 that blocks large particulate material from entering the heat exchanger 10. The mesh 42 forces the particulates into the bypass conduit 40. An optional deflector or blocker 44 may be located in the central core of the drain conduit. FIG. 7B illustrates a length of vertical orientated conduit 46 located at the top of the core of the drain conduit 32 and includes a plurality of holes 48. Grey water passes through the holes 48 to the exchanger 10. Particulate or larger debris is prevented from entering the exchanger and so passes down the drain conduit centre 49. FIG. 7C illustrates a cap 50, which blocks a center bypass channel 52. When the cap 50 is closed, grey water is forced to the sides where it falls onto vertically disposed helical double walled conduits 30. Optionally, the sides can have a mesh 51. The cap 50 can be operated manually or automatically. The cap 50 can be a twist cap, a magnetic plug, or powered by motor or hydraulic action. Referring to FIG. 7D illustrates a deflector 54, which forces all particulate matter to the sides of the heat exchanger 10. The deflector 54 is located such that there is always adequate clearance so that any material that moves through the top will fit around exchanger, after being forced to the sides. FIG. 7E illustrates a top view of the deflector 54. The deflector 54 is a cone with side plates 56. The cone forces water away from the conduit onto side plates 56, which drop then, falls onto the exchanger. A gap 58 between each side plate 56 is sufficiently large such that any material that fits through exchanger opening will fit through gap 58.

II. Serpentine Double Walled Heat Exchanger

Referring now to FIGS. 8, 8A, 9, and 9A, an alternative heat exchange apparatus 100 is illustrated. The heat exchange apparatus 100 comprises an elongate housing 102 having a housing inlet 104 and a housing outlet 106. The housing inlet 104 is connected to the drain trap 26 (not shown) or may be located anywhere downstream of the drain and defines the first fluid passageway for the first fluid, typically grey water. Typically, the heat exchange apparatus 100 is orientated horizontal relative to the ground so that the apparatus 100 can be located under, for example, the shower base. The elongate housing 102 includes two sidewalls 108 having a plurality of openings 110 therein. The openings 110 are arranged in groups of two along the sidewalls 108 and include an upper set 112 and a lower set 114. The lower set 114 are staggered away from the upper set 112, although it is possible that the upper and lower sets 112 and 114 can be located collinear with each other.

Referring to FIGS. 7, 7A and 8, at least one serpentine double wall conduit 116 is connected to the elongate housing 102 and passes through the upper set 112 of openings 110. A first plurality of conduit elbows 118 extend away from the sidewalls 108 along substantially the entire length of the elongate housing 102. A second serpentine double wall conduit 120 is connected to the elongate housing 102 and passes through the lower set 114 of openings 110. A second plurality of conduit elbows 122 extend away from the sidewalls 108 along substantially the entire length of the elongate housing 102. Additional serpentine double wall conduits can be used depending upon the application that is contemplated by the user. In the examples illustrated, a substantial portion of the serpentine conduits 116, 120 is located inside the elongate housing 102 and is thus able to contact the grey water, which flows through the housing 102. It is also possible that all of the serpentine conduits 116, 120 are located inside the elongate housing, thereby eliminating the conduit elbows exterior of the housing. This example is useful in applications where a more streamlined heat exchange apparatus is needed in, for example, space restricted locations.

Referring now to FIG. 8A, a plurality of fins 124, which may be corrugated along their surface, are mounted around the outer wall of the serpentine conduits 116, 120. The fins 124 are disposed parallel to each other and extend substantially the entire length of the elongate housing 102. The serpentine conduits 116, 120 and the fins 124 are located in the lower portion of the housing 102 such that they define a gap 126 thereabove of sufficient size to allow the use of cleaning tools or inspection of the apparatus during routine maintenance. A cap 128 is mounted over the elongate housing 102, which can be easily removed to expose the serpentine conduits 116, 120 and the fins 124. For ease of illustration, the openings 110 described are shown in the outer fin 124 and correspond to the openings in the adjacent sidewall 108.

Optionally, a low voltage heating wire, heating coil or heating tape (not shown) may be located inside the conduit 116. The heating wire may serve to increase turbulence (see below) of the cold water flowing in the conduit and/or increase the cold water temperature so that the heat exchanger 100 can provide all the heat required for the application (i.e. no longer passive and does not need to be combined with an external heating system). As described above in the heat exchange apparatus 10, a ventable leak passageway is located between the inner and outer conduits. The grey water when it flows along the second fluid passageway contacts the serpentine conduits 116, 120 and the fins 124 to effect heat transfer to the cold water fluid flowing in the serpentine conduits 116, 120 across their respective outer and inner conduit walls.

III. Turbulators

Referring now to FIGS. 10A through 100 and FIGS. 11A through 110, the drain conduit 32, the helical conduits 30A, 30B and 30C, and the serpentine conduits 116, 120 can be used with or without turbulators of the type known in the art. In particular, as seen in FIG. 10A, all or a portion of the inner wall of the conduits may have grooves, which enhance cold water turbulence. Also, as seen in FIGS. 10B and 100, corrugated or spiral conduits may also enhance the thermal energy transfer surfaces of the drain conduit. Turbulator inserts, as seen in FIG. 11A through G, known to those skilled in the art may also be used to enhance thermal energy transfer. FIGS. 11A through C illustrate examples of the turbulator inserts that include a twisted plastic or sheet materials with variable pitch. The greater the pitch, the more turbulence, more pressure loss and therefore higher heat transfer. Surface patterns such as herringbone or straight patterns may also be added to the inserts, as seen in FIGS. 11B and C. Twisted wire turbulators or rope as seen in Figure D, whereas a mixing nozzle insert for use at a nozzle entry located in the cold water conduit are also useful, as seen in FIGS. 11E and F. FIG. 11G is another type of turbulator design, which is manufactured by Statomix™. Additional turbulator designs are also useful for location in the grey water passageway is illustrated in FIG. 12A through C. In one example, FIG. 12A, fins are located exterior of the cold water conduit and project into the grey water passageway to cause turbulation of the grey water. FIG. 12B is an insert, which can be located inside the grey water passageway and may include holes through which the cold water serpentine or helical conduits can pass. The insert includes a surface pattern, which causes turbulation of the grey water. FIG. 12C is a torpedo-shaped insert, which may be located in the grey water passageway to effect turbulation of the grey water. FIG. 12D is a helical double wall torpedo insert, which when located in the grey water passageway causes turbulation of the grey water. The configuration of the torpedo-shaped inserts simulates grey water movement in a direction orthogonal to the ground.

As illustrated in FIG. 12E, a turbulator that is manufactured by Koflo is available in short lengths for purpose of mixing fluids. It is possible to manufacture a longer version of this for creating turbulence in cold water in our heat exchangers. The turbulator includes a plurality of half circles connected in a X pattern at each centre of the half circle. This design forces water to mix in two directions, i.e. left handed and right handed competing threads.

The flow of fluids can be passive, i.e. by gravity or can flow under the influence of pressure, either above or below atmospheric pressure. The heat exchange apparatus described herein are also self-draining. Moreover, due to their design, the helical can be located directly in a grey water pathway with or without the use of pre-filtration to remove particulate debris. Additional clog reduction features may include hair deflectors, non-stick coatings on the thermal transfer surfaces, or, in the case of the fins 126, the fins may have polished knife edges.

In one example, grey water flows over the three helical conduits, by gravity, such that it exchanges its heat (typically about 40° C.) to the source of cold water flowing through the conduits located in intimate contact with the drain conduit. In certain examples, higher fluid temperatures (>100° C.) may be used to also exchange thermal energy to cold water so as to generate steam. The heat exchange takes place across a thin (typically from about 1/1000 inch to about ⅕ inch thickness) double wall arrangement. The cold water flowing in the first cold water passageway is heated to produce warmed water, which may then be stored in a storage tank or communicated to a mixing valve in a shower or bath system. Advantageously, the heat exchange apparatus is constructed from inexpensive materials and when installed is essentially maintenance-free. The grey water conduits (pipes) used are standard 1.5 to 4 inch and are universally retrofittable into existing plumbing systems with the minimum of disruption to the household.

At least one of the thermal transfer surfaces is uneven. In one example, one thermal transfer surface is corrugated and defines a plurality of fin-like peaks (or blades) and troughs that extend longitudinally along the channel member 30 between the first and second end portions.

IV: Film Heat Exchanger

Referring now to FIGS. 13, 14 and 15, an alternative heat exchange apparatus is shown generally at 200. The heat exchange apparatus 200 is for applications that typically require the heat exchange apparatus to be located horizontal to the ground. The heat exchange apparatus 200 comprises an elongate housing 201 having an outer shell 202, a drain plate inlet 204, a drain plate outlet 206 and a drain plate 208. The drain plate inlet 204 can be connected to the drain trap 26, as described above. A plurality of double walled conduits 210 extend in parallel along the drain plate 208. A plurality of conduit inlets 212 are located at one end of the drain plate 208 and a plurality of conduit outlets 214 are located at another end of the drain plate 208 The conduits 210 are double walled as described above for the heat exchange apparatus 10 and 100. The conduits 210 define the first fluid passageway for the cold water. The drain plate 208 has a drain plate surface 216 through which at least a portion of the double wall conduits 210 extend. The drain plate surface 216 is of sufficiently large area to define the second fluid passageway for the second fluid such that the second fluid flows as a fluid film along the second fluid passageway and effects heat transfer to the first fluid flowing in the first fluid passageway across the inner and outer conduits of the conduits 210.

The drain plate 208 may be angled to provide a slope along the sides of the plate at the front end and a raised portion at the back end so as to force the grey water towards the conduits located at the extreme edges of the drain plate, and yet maintains the ability of the heat exchanger to self drain.

Another example the heat exchange apparatus 200 is shown in FIGS. 15A, 15B, 16 and 16A in which a plurality of serpentine conduits 210A, 210B, 210C and 210D are fully located inside the elongate housing 201 and are located close to each other, yet with a space between each conduit to allow waste grey water to flow thereover. The drain plate surface 216 is sufficiently large to create a thin film of grey water as described above. The elongate housing 201 is located inside a shell 203, which includes a gradual entry, and gradual exit which reduces clogging risk.

The heat exchange apparatus 200 can be made using plates that are die formed such that they create the same flow path as if in conduits. The double wall plates with serpentine flow paths can then be formed and welded to create a vertical cylinder as another construction for the vertical helical heat exchanger 10. Additionally, the same plates can also be made using a thermally conductive injection moulded plastic.

The horizontal film heat exchanger 200 can be located underneath a shower floor having a false drain, which lead to the true drain. Alternatively, the drain plate is located on the floor of the shower and is able to directly capture heat from grey water as it flows thereover. Additionally, the heat exchanger 200 may be incorporated directly into either a dishwasher or a washing machine or any other appliance, which uses hot water.

Built-in options may be included within any of the heat exchange apparatuses described herein in order to increase overall system performance and durability. These options include thin wall elements; laminar flow disruptor elements; check valve systems; one or more external level indicators; anti scaling capabilities such as, for example, mechanical devices and passage configurations to reduce scaling, anti-scaling coatings, vibration, chemical, and electrical means; anti corrosion means such as, for example, electrical, chemical, anodic, cathodic, and coatings; and water hammer protection such as, for example, shock absorbers, flexible or relatively soft and elastic cold water circuit components. Additional features may include use of an insulating shell on the systems and subsystems. System leaks and malfunctions can be detected in a variety of ways using, for example, relative flow measurement and/or pressure transducers and gauges located at strategic points in the heat exchange apparatus. The heat exchangers may be self draining in both horizontal and vertical positions. If electric power is required for monitoring or control equipment, power sources such as batteries, thermoelectric, or micro-turbines can be advantageously used in combination or alone.

It is known that greater thermal transfer performance and ease of manufacturing are obtained by using a thin formed sheet material in the manufacturing process of the heat exchanger components. Using thin wall stainless steel composite sheets of approximately 0.015″ to 0.035″ thicknesses in heat exchanger apparatuses provides low resistance to burst due to possible excessive high internal cold water pressure, such as those commonly used in household or industrial plumbing systems.

The aforesaid heat exchangers can be used in many applications such as for example in household shower/baths, in washing machines and the like. In the design for use in household shower, grey water typically drains at 10 litres/hour.

Advantageously, the serpentine conduits described for heat exchanger 100 and 200 (FIGS. 16 and 16A) increase the dwell time of cold water in contact with the grey water. This is in contrast with elongate conduits and the bends outside the grey water. Thus, cold water conduit bends are located inside the grey water passageway so that the dwell time is increased and cold water never leaves the heat transfer area while inside the exchanger.

V. Manifolds

Referring now to FIGS. 17A and 17B, a manifold 300 is illustrated which provides double wall leak off and can be used to mount and secure the double wall conduits 210 of any of the heat exchange apparatuses described herein to the respective apparatuses. The manifold 300 comprises an outer conduit connector 302, an inner conduit connector 304 and a flow director 306. The connectors 302, 304 include openings 308 for receiving the double wall conduits 210 therein. The outer conduit connector 302 and the inner conduit connector 304 include knurled surfaces 309, which provide a double wall leak passageway 310 through which cold water can flow in the event that the integrity of the double wall conduit is compromised. The manifold 300 may be a double manifold located at either end of heat exchange apparatus and may be for single or multiple circuits of conduits. Additionally, cold water can flow into and out of the same manifold or in an independent manifold.

VI. Gravity Thermosyphon

Referring now to FIG. 18, a gravity thermosyphon 400 is contemplated for use with the heat exchange apparatuses as described herein. The thermosyphon 400 comprises a bath 402 of refrigerant material such as ethylene glycol in which the second fluid passageway carrying the grey water is located. Located above the second fluid passageway 40 are the double walled conduits, such as for example, the conduits 210 such as those described herein. A deflector 403 may be located between the conduits 210 and the second fluid passageway (the grey water passageway) 40. The grey water flowing along the second fluid passageway 40 causes the refrigerant to heat up and evaporate (see wavy lines). The evaporated refrigerant 405 contacts the double wall conduits 210 carrying the cold water 25, which flows into the conduits 210 at a first end 404. The vaporized refrigerant 405 condenses on contact with the cold conduits 210 and returns to the bath 402. The thermal energy from the vaporized refrigerant thermally transfers to the cold water so that it exits the conduit 210 at a second end 406 at a higher temperature. The process repeats so long as the grey water and the cold water flow in their respective passageways.

VII: Alternative Film Heat Exchanger

Referring now to FIGS. 19 and 20, an alternative embodiment of a heat exchange apparatus is shown generally at 500. The heat exchange apparatus 500 comprise one or more single or double walled conduits 502, as described herein, which define a first fluid passageway 504 for a first fluid at a first temperature. A drain plate 506 having a drain plate inlet 508 and a drain plate outlet 510 and a drain plate surface 512 is located either generally orthogonal to the ground, generally horizontal to the ground or angled relative to the ground to create an incline. A portion of the single or double walled conduits 502 is located in intimate contact with the drain plate 506, which has a surface of sufficient area to define a second fluid passageway 514 along which the grey water flows by gravity. The location of the conduits 502 against the drain plate 506 provides a passageway of the grey water which flows as a film 516 over the conduits 502 to efficiently effect heat transfer to the first fluid flowing in the first fluid passageway across the single or double walled conduits 502. The drain plate inlet 508, as best illustrated in FIG. 20, is connected to an outer shell 520, which is located over the conduits 502. The drain inlet 508 is shaped to force the grey water along a deviated path 518 towards the conduits 502 to create the film 516 thereagainst thereby effecting heat transfer across the wall or walls of the conduits 502. Thus, heat exchange occurs on only one side of the apparatus. Furthermore, the width of the drain plate 506 is larger than the width of the feed pipe (not shown) so as to create the film 516, which flows along the second fluid passageway. As above, turbulators can be used inside the cold water passageway to increase heat exchange. The surfaces of the heat exchange apparatus 500 can be coated with a non-stick coating such as TEFLON to prevent fouling by debris.

As best illustrated in FIG. 21, any one of the heat exchange apparatus described herein can be located in a trench drain 520. Common manifolds 522 and 524 are connected to their respective cold water inlets and warmed water outlets. In the example illustrated, grey water enters the trench drain 520 and passes downwardly over the conduits and effects heat exchange. For most applications, the width of the trench drain is about 12-inches, whereas the height is about 8-inches. The train drain 520 is open, which advantageously allows ease of installation of the heat exchanger and ease of maintenance.

A hybrid water heater may be used in combination with any of the above described heat exchangers by using electric heating elements or wires directly in the cold water conduits or by wrapping a heating coil around the outside of the conduits. This can be combined with a solar panel to make a low cost solar water heater. It can be low voltage to avoid the risk of electric shock. Electric heaters have very high efficiency because almost all of the electrical energy is converted into heat, which heats the water. Tankless electric heaters often cannot supply enough capacity of hot water because of either the size of the heater that would be required or the power. However, a hybrid system, which combines a heat exchanger with a heating element to provide more heating capacity, may advantageously replace a standard water heater.

Other Embodiments

It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the present discovery and scope of the appended claims. 

1. A heat exchange apparatus, the apparatus comprising: a) at least one double walled conduit having an outer conduit and an inner conduit located coaxially inside the outer conduit, and defining a first fluid passageway for a first fluid at a first temperature; and b) a drain defining a second fluid passageway for a second fluid at a second temperature, the double walled conduit being located in the drain and downstream of the second fluid flowing therethrough, such that the second fluid when flowing in the second fluid passageway effects heat transfer to the first fluid flowing in the first fluid passageway across the inner and outer conduits.
 2. The apparatus, according to claim 1, in which the inner conduit includes an outer wall, the outer conduit includes an inner wall, the outer wall being located against the inner wall to define a leak passageway therebetween.
 3. The apparatus, according to claim 2, in which the outer conduit includes an inner knurled surface that is pressed against the outer wall of the inner conduit to define the leak passageway.
 4. The apparatus, according to claim 1, in which the double walled conduit is helical.
 5. The apparatus, according to claim 1, includes an outer helical double wall conduit, a central helical double wall conduit and an inner helical double wall conduit.
 6. The apparatus, according to claim 5, in which the outer, central and inner helical double walled conduits are assembled concentrically.
 7. The apparatus, according to claim 6, in which the circumference of the helices of the double wall conduits decreases from the outer conduit to the inner conduit.
 8. The apparatus, according to claim 5, in which the helical conduits are coiled in the same direction.
 9. The apparatus, according to claim 8, in which the helical conduits are coiled in a counterclockwise direction.
 10. The apparatus, according to claim 8, in which the helical conduits are coiled in a clockwise direction.
 11. The apparatus, according to claim 6, in which each conduit includes a bend located at an upper end of the assembled helical conduits.
 12. The apparatus, according to claim 1, in which the first and second fluids flow in a contra-flow manner through the heat exchange apparatus.
 13. The apparatus, according to claim 1, in which the drain is a drain conduit.
 14. The apparatus, according to claim 13, in which the drain conduit includes an upper drain portion connected to a drain trap.
 15. The apparatus, according to claim 13, includes a bypass conduit connected to the drain conduit, the bypass conduit having a mesh for blocking particulate material.
 16. The apparatus, according to claim 13, includes a deflector located in a central core of the drain conduit.
 17. The apparatus, according to claim 13, includes a vertically orientated conduit located at the top of the central core of the drain conduit and having a plurality of holes located therein.
 18. The apparatus, according to claim 17, in which a cap is located on top of the vertically orientated conduit for temporarily blocking a central bypass channel.
 19. The apparatus, according to claim 18, in which the cap is operated manually or automatically.
 20. The apparatus, according to claim 16, in which the deflector is a cone with side plates for forcing the second fluid away from the conduit.
 21. The apparatus, according to claim 1, in which a plurality of helical conduits are stacked adjacent each other in the drain conduit.
 22. The apparatus, according to claim 21, includes four stacked helical conduits.
 23. The apparatus, according to claim 21, in which the helical conduits include a common first fluid inlet and a common first fluid outlet.
 24. The apparatus, according to claim 1, is orientated orthogonal to the ground.
 25. The apparatus, according to claim 1, is orientated horizontal to the ground.
 26. The apparatus, according to claim 1, is connected to a drain trap in a shower.
 27. The apparatus, according to claim 1, in which the double walled conduit is serpentine.
 28. The apparatus, according to claim 27, in which at least a portion of the serpentine double walled conduit is located in the drain.
 29. The apparatus, according to claim 27, in which at least one serpentine double wall conduit is connected to an elongate housing having two sidewalls and passes through an upper set of openings located in the sidewalls.
 30. The apparatus, according to claim 29 in which a first plurality of conduit elbows extend away from the sidewalls along substantially the entire length of the elongate housing.
 31. The apparatus, according to claim 29, in which a second serpentine double wall conduit is connected to the elongate housing and passes through a lower set of openings located in the sidewalls.
 32. The apparatus, according to claim 31, in which a second plurality of conduit elbows extend away from the sidewalls along substantially the entire length of the elongate housing.
 33. The apparatus, according to claim 29, in which a plurality of fins are mounted around the outer wall of the serpentine conduits, the fins being disposed parallel to each other and extend substantially the entire length of the elongate housing.
 34. The apparatus, according to claim 1, includes a turbulator located in the drain or the helical conduit.
 35. The apparatus, according to claim 1, in which the drain is a drain plate having a drain plate inlet and a drain plate outlet and a drain plate surface through which at least a portion of the double wall conduit extends, the drain plate surface being of sufficient area to define the second fluid passageway for the second fluid such that the second fluid flows as a fluid film along the second fluid passageway.
 36. The apparatus, according to claim 35, in which a plurality of double walled conduits extend parallel along the drain plate.
 37. The apparatus, according to claim 35, in which the drain plate is orientated horizontal relative to the ground.
 38. The apparatus, according to claim 35, in which the drain is angled relative to the ground.
 39. The apparatus, according to claim 35, includes a plurality of serpentine double walled conduits.
 40. The apparatus, according to claim 39, in which the serpentine conduits are sufficiently spaced apart top allow the second fluid to flow thereover.
 41. The apparatus, according to claim 1, in which the drain is a trench drain.
 42. The apparatus, according to claim 1, in which the first fluid is cold water.
 43. The apparatus, according to claim 1, in which the second fluid is grey water.
 44. The apparatus, according to claim 1, in which a heating wire is located inside the double walled conduit.
 45. The apparatus, according to claim 1, in which a heating wire is located around the double walled conduit.
 46. A heat exchange apparatus comprising: a) at least one single walled conduit defining a first fluid passageway for a first fluid at a first temperature; and; and b) a drain plate having a drain plate inlet and a drain plate outlet and a drain plate surface against which at least a portion of the single wall conduit is located in intimate contact, the drain plate surface being of sufficient area to define a second fluid passageway for a second fluid such that the second fluid flows as a fluid film along the second fluid passageway so as to effect heat transfer to the first fluid flowing in the first fluid passageway across the single walled conduit.
 47. A heat exchange apparatus comprising: a) at least one single walled conduit defining a first fluid passageway for a first fluid at a first temperature; and; and b) a drain plate having a drain plate inlet and a drain plate outlet and a drain plate surface against which at least a portion of the single wall conduit is located in intimate contact, the drain plate being located generally orthogonal to the ground, the drain plate surface being of sufficient area to define a second fluid passageway for a second fluid such that the second fluid flows as a fluid film along the second fluid passageway so as to effect heat transfer to the first fluid flowing in the first fluid passageway across the single walled conduit. 48.-109. (canceled) 